Ultrasonographic assessment of in utero fetal presentation, position and posture can be essential: case report.

Objective Summary

• This clinical case report demonstrates how late-stage transrectal ultrasound can be used to evaluate the position, presentation, and posture of a fetus in utero in a horse, aiding in diagnosis and guiding management.
• The report details a case where abnormal fetal posture associated with musculoskeletal and cerebellar abnormalities was identified by ultrasound, resulting in a planned cesarean section.

Detailed Explanation

Background and Goals

• Understanding fetal presentation (the part of the fetus closest to the birth canal), position (orientation relative to the mare’s pelvis), and posture (flexion or deviation of limbs and head) is crucial before foaling.
• Ultrasound, particularly late transrectal examination, is valuable for assessing these fetal parameters in horses.
• This case report aims to highlight the use of ultrasound to diagnose abnormal fetal posture and presentation, and how this information can guide clinical decisions.

Case Details

• Subject: A 7-year-old Gypsy Vanner mare at 339 days of gestation (normal gestation ~340–365 days).
• Physical findings: Detected a bony fetal structure cranial (toward the head) of the cervix; no palpable head or limbs; minimal fetal movement observed.
• Initial suspicion of abnormal fetal presentation and posture due to limited palpable anatomy and minimal movement.

Diagnostic Imaging Approach

• Transrectal Ultrasound: Key in identifying the fetal presentation as cranial (head positioned toward the cervix, but not low enough for normal birth preparation) with the fetus’s neck deviated to the right and head flexed, indicating abnormal fetal posture.
• Transabdominal Ultrasound: Confirmed the cranial presentation and revealed that the fetus was positioned high inside the mare’s pelvis, which could complicate normal delivery.

Management and Outcome

• At 349 days gestation, when parturition began, a cesarean section was elected due to the abnormal presentation and posture identified on ultrasound.
• The foal was delivered stillborn and covered with meconium (indicating fetal distress/stress during labor).
• Post-mortem findings in the foal included severe neurological abnormalities (cerebellar hypoplasia, reduced Purkinje cells, and gliosis) and musculoskeletal deformities (arthrogryposis, scoliosis, abnormal occipital condyles, and sternum deformity).
• Genetic analysis revealed abnormalities potentially contributing to the foal’s developmental defects and fetal malposition.
• The mare recovered well post-cesarean and was discharged home after 7 days.

Significance and Clinical Takeaways

• This case highlights the critical role of late transrectal ultrasound in equine obstetrics to assess fetal presentation, position, and posture.
• Early and accurate ultrasound diagnosis allowed for planned cesarean section, which likely prevented complications in the mare during parturition despite the foal being non-viable.
• Abnormal fetal postures may be associated with serious underlying developmental anomalies affecting both the nervous and musculoskeletal systems.
• Using ultrasound in late gestation can optimize management plans and improve outcomes for mares by anticipating difficult births.